XenServer is not a suitable platform for production yet

Built two XenServer using version 5.5 Update 2 and played with it for a few days. The advantage of XenServer over Hyper-V and VMware ESX/i is that it provides an environment supports live migration without a separate management server (vCenter in VMware's case), and it is free. Beyond this, for example HA, are all paid features and requires a separate management server.

Its disadvantage are not very obvious but they show themselves after some playing. Unfortunately these advantages are deal killers to a production environment.

1. Snapshot takes same amount of disk space as original VM. Actually it is a copy of VM.

2. Unable to revert to a snapshot by simple mouse clicks. You need to tear down the original VM, then use the snapshot as template to create a new VM. The new VM needs to be reconfigured.

3. Difficult to configure multiple NICs and multiple LANs. Need to use local command line or local console menu workaround

4. Host will lose NIC configuration after forced shutdown or unplugging cable

5. Disk space management is backward. After using snapshots for some period of time, wasted disk space need to be reclaimed with special utility. The reclaim process requires all VMs on the host to be off.

6. Paravirtualization swaps out OS kernel, cause reliability, compatibility, portability and scalability issues.

7. Paravirtualization is only available for limited OS and versions based on available templates. It is very difficult to create templates from scratch for new OS by users. Citrix does not regularly release new templates.



The bottom line: Citrix XenServer, at present stage, only provides best price value (free) for non-critical multi-host environment with limited OS choice and slow update cycle.